1. Nature of the Invention
This invention relates to processes for catalytically converting olefins into gasoline and distillate fractions, particularly by contacting the olefins with crystalline zeolites.
2. Brief Description of the Prior Art
The conversion of olefins to gasoline and distillate products is known to those skilled in the art. For example, U.S. Pat. No. 3,960,978 discloses a process wherein gaseous olefins in the range of ethylene to pentene, either alone or in admixture with paraffins are converted into an olefinic gasoline blending stock by contacting the olefins with a catalyst bed made up of a ZSM-5 type zeolite. In a related manner, U.S. Pat. Nos. 4,021,5902 and 4,150,062 disclose processes for converting olefins to gasoline components. The process as currently developed recycles cooled gas (propane and butane) from a high-temperature, high-pressure separator downstream of the catalyst bed back into the reaction bed where additional olefins are converted to gasoline and distillate products. If the reaction of the olefins in converting them to distillate and gasoline is allowed to progress in the catalyst system without any measures taken to prevent the accumulation of heat, the reaction becomes so exothermically accelerated as to result in high temperatures and the production of undesired byproducts.
In present processes for converting olefins to gasoline components as noted previously, the warm effluent stream from the zeolite bed ordinarily is heat-exchanged with the incoming feedstock and then passed to a high-pressure gas-liquid separator where condensed liquid is separated and carried to a distillation column for further processing into a gasoline product. The overhead gas consisting primarily of butane and propane is compressed as a gas and recycled in part to the conversion process while the remainder is used for other purposes.